<!--$Id: db_del.so,v 10.51 2007/10/24 16:06:06 bostic Exp $-->
<!--Copyright (c) 1997,2008 Oracle.  All rights reserved.-->
<!--See the file LICENSE for redistribution information.-->
<html>
<head>
<title>Berkeley DB: Db::del</title>
<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++">
</head>
<body bgcolor=white>
<table width="100%"><tr valign=top>
<td>
<b>Db::del</b>
</td>
<td align=right>
<a href="../api_cxx/api_core.html"><img src="../images/api.gif" alt="API"></a>
<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td>
</tr></table>
<hr size=1 noshade>
<tt>
<b><pre>
#include &lt;db_cxx.h&gt;
<p>
int
Db::del(DbTxn *txnid, Dbt *key, u_int32_t flags);
</pre></b>
<hr size=1 noshade>
<b>Description: Db::del</b>
<p>The Db::del method removes key/data pairs from the database.  The
key/data pair associated with the specified <b>key</b> is discarded from
the database.  In the presence of duplicate key values, all records
associated with the designated key will be discarded.</p>
<p>When called on a database that has been made into a secondary index
using the <a href="../api_cxx/db_associate.html">Db::associate</a> method, the Db::del method deletes the
key/data pair from the primary database and all secondary indices.</p>
<p>The Db::del method will return <a href="../ref/program/errorret.html#DB_NOTFOUND">DB_NOTFOUND</a> if the specified key is not in the database.
The Db::del method will return <a href="../ref/program/errorret.html#DB_KEYEMPTY">DB_KEYEMPTY</a> if the database is a Queue or Recno database and
the specified key exists, but was never explicitly created by the
application or was later deleted.
Unless otherwise specified, the Db::del method
either returns a non-zero error value
or throws an exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
</p>
<b>Parameters</b> <br>
 <b>flags</b><ul compact><li>The <b>flags</b> parameter is currently unused, and must be set to 0.</ul>
 <b>key</b><ul compact><li>The key <a href="../api_cxx/dbt_class.html">Dbt</a> operated on.</ul>
 <b>txnid</b><ul compact><li>If the operation is part of an application-specified transaction, the
<b>txnid</b> parameter is a transaction handle returned from
<a href="../api_cxx/txn_begin.html">DbEnv::txn_begin</a>; if the operation is part of a Berkeley DB Concurrent Data Store group, the
<b>txnid</b> parameter is a handle returned from
<a href="../api_cxx/env_cdsgroup_begin.html">DbEnv::cdsgroup_begin</a>; otherwise NULL.
If no transaction handle is
specified, but the
operation occurs in a transactional
database,
the operation will be implicitly transaction protected.
</ul>
<br>
<br><b>Errors</b>
<p>The Db::del method
may fail and throw
<a href="../api_cxx/except_class.html">DbException</a>,
encapsulating one of the following non-zero errors, or return one of
the following non-zero errors:</p>
<br>
<b>DB_REP_HANDLE_DEAD</b><ul compact><li>The database handle has been invalidated because a replication election
unrolled a committed transaction.</ul>
<br>
<br>
<b>DB_REP_LOCKOUT</b><ul compact><li>The operation was blocked by client/master synchronization.</ul>
<br>
<br>
<b>DB_SECONDARY_BAD</b><ul compact><li>A secondary index references a nonexistent primary key.</ul>
<br>
<br>
<b>EACCES</b><ul compact><li>An attempt was made to modify a read-only database.</ul>
<br>
<br>
<b>EINVAL</b><ul compact><li>An
invalid flag value or parameter was specified.</ul>
<br>
<p>If a transactional database environment operation was selected to
resolve a deadlock, the Db::del method will fail and
either return <a href="../ref/program/errorret.html#DB_LOCK_DEADLOCK">DB_LOCK_DEADLOCK</a> or
throw a <a href="../api_cxx/deadlock_class.html">DbDeadlockException</a> exception.</p>
<p>If a Berkeley DB Concurrent Data Store database environment configured for lock timeouts was unable
to grant a lock in the allowed time, the Db::del method will fail and
either return <a href="../ref/program/errorret.html#DB_LOCK_NOTGRANTED">DB_LOCK_NOTGRANTED</a> or
throw a <a href="../api_cxx/lockng_class.html">DbLockNotGrantedException</a> exception.</p>
<hr size=1 noshade>
<br><b>Class</b>
<a href="../api_cxx/db_class.html">Db</a>
<br><b>See Also</b>
<a href="../api_cxx/db_list.html">Databases and Related Methods</a>
</tt>
<table width="100%"><tr><td><br></td><td align=right>
<a href="../api_cxx/api_core.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
</td></tr></table>
<p><font size=1>Copyright (c) 1996,2008 Oracle.  All rights reserved.</font>
</body>
</html>
